River Rescue: New STP at Varanasi to curb sewage discharge into the Ganga

New STP at Varanasi to curb sewage discharge into the Ganga

India’s largest river, the Ganges, provides water to over 40 per cent of the country’s population across 11 states, supporting the lives of 500 million people. No other river in the world contributes so much to human water needs. However, the pollution in the river has been a major cause for concern and poses significant threats to human health and the environment.

A major step to clean and conserve the river was taken in 1986 with the launch of the Ganga Action Plan. Namami Gange, an integrated Ganga development project, was launched in July 2014 with a Rs 200 billion budget for five years. It envisaged short-, medium- and long-term activities for cleaning the river.

Short-term activities covered the development of cremation ghats and cleaning of the river surface; medium-term activities included establishing new sewage treatment plants (STPs) and effluent treatment plants (ETPs), and upgrading the existing plants; and long-term activities envisaged the restoration and maintenance of the ecological and geological integrity of the river.

In Varanasi, sewage and wastewater management has been a major challenge for authorities. The city, reportedly, generates about 300 million litres per day (mld) of sewage. The wastewater collected and diverted to the city’s existing STPs is just 33 per cent of the total wastewater, while the remaining 67 per cent is discharged into the river Ganga and its tributary Varuna. The sewage generation is expected to increase up to 400 mld by 2035 with the rise in population.

The Ministry of Water Resources, River Development and Ganga Rejuvenation and its implementing arm the National Mission for Clean Ganga (NMCG) have taken up several projects for treating wastewater in Varanasi and improving the overall water quality. At present, the city has three operational STPs, which were set up under Phase-I of the Ganga Action Plan (GAP). They have a total sewage treatment capacity of 102 mld.

Apart from these, three new STPs were sanctioned in GAP Phase-II under different schemes to increase the total sewage treatment capacity to 412 mld. One of the STPs has been set up at Goithaha under the Jawaharlal Nehru National Urban Renewal Mission. The plant, with a capacity to treat 120 mld of wastewater, will check the flow of untreated sewage disposal from the trans-Varuna area into the river Ganga. The second, with a capacity of 140 mld, has come up at Dinapur with project assistance from the Japanese International Cooperation Agency and the third is being constructed at Ramna. These projects will minimise the disposal of untreated sewage into the river Ganga from Varanasi.

Key features of the Goithaha STP

The Goithaha STP is one-of-its-kind and has been built by Larsen and Toubro (L&T) at a cost of Rs 1.18 billion. The project involves the interception and diversion works where small rivers, rivulets and drains are intercepted before they empty into the main river and are diverted to the STP so that the water that finally drains into the main river is clean.

Designed by the water and effluent treatment business vertical of L&T Construction, the STP is based on the latest sewage treatment technology, Sequential Batch Reactor (SBR). The plant, consisting of six SBR tanks, will not only prevent the sewage water from entering the river Ganga, but will also treat and recycle close to 4,380 litres of wastewater. The treated water will be made available for irrigation.

The environmental standards for the STP conform to the stringent effluent discharge norms of biological oxygen demand (BOD) of less than or equal to 10 milligrams and total suspended solids (TSS) of less than or equal to 10 milligrams per litre. L&T will be responsible for the operations and maintenance of the plant for five years.

The STP with its 149 km pipeline of the sewage network is fully automated. To deliver the sewage to the STP for necessary treatment, an intermediate pumping station and a main pumping station have been built. The treated effluent is disposed of in the nearby canal for irrigation purposes.

Currently, the plant is performing below capacity as it is only getting 20-25 mld of sewage for treatment. This is because only about 25,000 of the total 50,000 households have been connected to sewer lines. Full capacity utilisation will be possible only when all the households are connected to the STP through sewer lines. All the drains discharging their sewage into the river Varuna have been capped.

In sum

A check on the discharge of sewage into the river will be possible once the 50 mld STP in Ramna is completed. This will transform Varanasi into the first city with zero discharge of pollutants into the river Ganga. The total sewage treatment capacity will go up to 412 mld, adequate for meeting the sewage treatment needs of the city till 2035.